Leveling devices in the past have been employed for adjustably supporting loads of varying sizes and weights. The level conditions of machine tools, production equipment, and, more recently, nuclear reactors, have presented a critical need for preciseness. Although several levelers are usually used to obtain this precise condition, full compensation for uneven or non-level supporting planes has been difficult, if possible, to attain. The result of a non-level condition will result in load shifting and an accompanying impairment of operation or other serious and costly consequences.
Previous attempts to compensate for supporting plane unevenness and slope have included the combination of wedges and spherical surfaces, as taught in U.S. Pat. No. 3,306,562, but these earlier devices had a limited range of adjustability and stability. Usually the supporting plane upon which the leveling device was to rest required substantial preparation to approach near levelness.